Punching and forming tool with straightening facility for metal strip

ABSTRACT

A tool for the punching and forming of a metal strip while simultaneously straightening same under elevated pressure, comprises a pressure plate adapted to urge the metal strip against a matrix plate under hydraulic pressure and forming a guide for a plurality of punches displaceable by advance of the member carrying the hydraulic devices toward the matrix plate. Springs between the matrix plate and the guide plate urge the latter in the opposite direction. The pressure-guide plate is provided with an insert cooperating with a recess in the matrix plate to deflect the metal strip during the forming operation.

United States Patent 1 Nowak [451 Sept. 18,1973

[ PUNCI-IING AND FORMING TOOL WITI-I STRAIGI'ITENING FACILITY FOR METAL STRIP [75] Inventor: Edmund Nowak, Warszawa, Poland [73] Assignee: Zaklad Doswiadczalny Pras Automatycznych HYDOMAT przy Zakladach Mechanicznych Tarnow, Warszawa, Poland [22] Filed: June 7, 1971 211 App], No.: 150,578

[30] Foreign Application Priority Data 3,435,653 4/1969 Scaletta 72/336 3,418,706 12/1968 White 1,952,195 3/l934 Candee 113/40 Primary ExaminerCharles W. Lanham Assistant Examiner-Robert M. Rogers Attorney-Karl F. Ross [57] ABSTRACT A tool for the punching and forming of a metal strip while simultaneously straightening same under elevated pressure, comprises a pressure plate adapted to urge the metal strip against a matrix plate under hydraulic pressure and forming a guide for a plurality of punches displaceable by advance of the member carrying the hydraulic devices toward the matrix plate.

Springs between the matrix plate and the guide plate urge the latter in the opposite direction. The pressureguide plate is provided with an insert cooperating with a recess in the matrix plate to deflect the metal strip during the forming operation.

2 Claims, 4 Drawing Figures H 46 45 1 21 460 450/ l 7' 4 2x f -Q/l\ g I I d l \24 M Patented Sept. 18, 1973 3,759,079

3 Sheets-Sheet 1 INVENTOR Y marl jams ATTORNEY Patented Sept. 18, 1973 3 Sheets-Sheet 2 Fig. 2.

fi l-I fee" c Fig.3.

INVENTOR 6 BY marl g, Q

ATTORNEY Patented Sept. 18, 1973 3 Sheets-Sheet 5 Fig.4.

INVENTOR BY 9M 9- ATTORNEY PUNCIIING AND FORMING TOOL WITII STRAIGII'IENING FACILITY FOR METAL STRIP This invention relates to the method of straightening of metal strips and forming of elements, consisting in that the tool pressure plate performs by its pressure the operation of forming, for instance of bevelling or bending at which these operations are effected simultaneously with operations of cutting the strip by punches in the tool.

The above method is implemented by the tool whose pressure-guide plate produces a very high pressure, owing to connecting it with hydraulic servo-motors located in the tool or in the press. Besides, the pressureguide plate is provided with inserts made of highquality steel, whose proper shaping permits obtaining the required geometry of elements being manufactured.

The simplication of the technology of tool making is ensured due to fastening of sleeves which guide punches in the pressure-guide plate by means of a plastic, for instance epidian. I

This invention relates to the method of straightening metal strips and forming elements by means of a tool pressure plate and a tool for implementing the method.

The tools known to date for forming metal strip are provided with punches guided directly or indirectly. In the case of direct guidance of punches, the guide plate is connected with a punch plate,permanently, through side washers, forming a box-type design.

In tools whose punches are guided directly, the guide plate is guided by means of columns connecting the lower tool plate with the upper plate.

In tools with indirect guidance of a punch the guide plate simultaneously functions as a pressure plate which presses the strip against the matrix plate and, is thus a pressure-guide plate.

The pressure of the pressure plate is obtained by disk shaped or spiral springs, or other elastic elements, or by a system of pneumatic servo-motors located in the upper portion of the tool and connected with the pressure plate.

Besides, both in box-type tools and in tools with indirect punch guidance, the operations of forming, e.g- .bending, and cutting are not effected in one location in the tool, but in specific portions thereof.

The main drawback of box-type tools is the fact that the metal strip introduced into the too], because of the position of the guide plate, is not pressed onto the matrix plate of the moment the operation of the punches begins; this negatively influences their durability and diminishes thereby the dimensional accuracy of the workpiece being manufactured.

A similar situation prevails in tools with indirect guidance of punches where the system of of springs or pneumatic servo-motors cannot generate an adequately high pressurev of the pressure guide plate to ensure the straightening of the strip, this makes it necessary to employ strip-straightening machines, whereby disadvantageous sag occurs and in this connection, special control devices must be applied.

Moreover, in tools with indirect punch guidance, the pressure-guide plate performs, together with the upper portion of the tool, a full stroke upwards equalling the idle stroke of the press, thereby requiring properly designed column ways and increasing the cost and weight of the tool.

In the tool aforementioned designs, a further drawback is that the size of the working zone of the tool is increased because of separation of the forming operation from the cutting operation.

The object of this invention is the elimination of all these disadvantages. A more specific object is to provide an improved method of metal/strip straightening and forming and a tool for carrying out this method which ensures a strong pressure of the pressure-guide plate, high durability, and accuracy of operation with simple construction.

According to the invention the high pressure of the strip against the matrix plate is obtained by means of hydraulic servo-motors located either in the press ta-' bles or in the punch plate, and by providing the matrix plate as the base of the punch plate.

The geometrical regularity of workpiece to be manufactured is obtained by mounting in the pressure-guide plate an insert or inserts of high-quality steel, the proper shaping of said inserts ensuring the forming operation, for instance bending and, straightening. The punches are located in the closest proximity to the inserts and enable a connection in one tool cycle of the forming operation and the cutting operation.

Moreover, in the tool according to invention the pressure-guide plate is guided on columns mounted in the lower tool plate, at which this plate is guided simultaneously in relation to the upper portion of the tool by means of punches, mounted in the punch plate.

Also the punches are guided in the pressure-guide plate by means of sleeves mounted in the said plate with the use of plastic, for instance Epidian.

The basic advantage of the tool according to the invention is the fact that it incorporates the positive features of box-type tools and tools with indirect punch guidance. First of all, the guiding of the pressure plate on setting columns in the lower part of the tool permits a limitation of its stroke upwards, i.e. the stroke of the plate can be adjusted to be of such a range, as to enable a free feed of the strip in to the tool and the ejection of the product.

The pressure-guide plate with its system of hydraulic servo-motors ensures a very high pressure of the strip against the matrix plate of the order of up to 50 percent of the total press pressure, thereby ensuring an ideal straightening of the strip in the working zone of the tool and enabling a simultaneous forming of the element being manufactured by means of inserts in the pressure-guide plate.

The mounting with the use of plastic in the pressureguide plate of guide sleeves for the punches, maintains the coaxiality of the punches and holes in pressure and punch plates, which improves the ease of assembly of the tool and increases the durability of the punches and matrix.

The increased durability of tool is also enhanced by the ideal straightening of the strip under strong pressure against the matrix plate.

The forming by means of a'pressure plate simplifies the restoration of the tool, such that the grinding of the matrix plates and of cutting punches only is needed.

The invention is illustrated in the drawing, in which:

FIG. 1 shows a section of the tool for straightening strips and forming of elements,

FIG. 2 shows a fragment of the tool with an insert in the pressure plate and adjoining cutting punches,

FIG. 3 shows an example of an element made by the tool, and

FIG. 4 shows the press with mounted tool according to invention.

As shown in FIG.1 the tool for forming and straightening of elements made of metal strips, consists of punch plate 3 and strap 27 connected with upper plate 2, pressure-guide plate 4, matrix plate 5, and base of matrix 6.

The pressure-guide plate is guided on columns 12, at which the clearance between the pressure plate and matrix plate is adjusted by means of washers l3 and screws 14 coarsely, and precisely by means of washers 11 and screws 10.

In the punch plate 3 are fastened punches l7,l7a,and 20, which punches are guided in the pressure plate by means of sleeves 16,16a, and 19, sealed in the said plate with plastic,e.g. Epidian 15,15a,l8.

The pressure-guide plate 4 presses the strip 24 against the matrix plate 5 by hydraulic servo-motors 8 and 9, located in the punch plate 3, strap 27 and upper plate 2, or in the working table 1 of the press.

The hydraulic servo-motors are connected with the pressure-guide plate 4 by means of pushers pistons 25 and 26. In the pressure-guide plate 4 are mounted inserts 21 cooperating with cut-outs or recesses 22. The pressure-guide plate 4 is maintained in the upper position by means of springs 23.

In FIG.2 is shown a fragment of the tool in working position during forming of an element, at which are shown the angle between l7830 and l5520 in the insert and angles ,6 in the cut-out of the matrix plate, and angle of inclination 8 between 4'and 015 of generatrix of the hole for punches in the matrix plate, which angles are decisive of the proper geometry of an element being formed.

In FIG.3 is illustrated the element made. The operation of the tool is as follows: a known feeding device introduces the strip to the tool. In the proper moment of the work cycle the strip is pressed on to the matrix plate by the pressure-guide plate 4 due to the action of servo-motors 8 and 9.

At the same time the insert or inserts 21 are forming the element: for instance they perform the operations of bending, or chamfering, or straightening, through the introduction of the strip to the cooperating cut-outs 22 in the matrix plate.

In the next moment of the work cycle the work table 1 begins the working stroke causing the penetration of punches into the strip and in the holes in the matrices and in result a final forming of the element.

After retraction of the table 1 and of the pressureguide plate 4 to the upper position, the strip is shifted in the tool forward, at which the leading edge of the strip ejects the formed element. The work cycle then starts again.

I claim:

I. A tool for the forming of a metal strip in a press having a base and a member movable in the direction of said base, said tool comprising:

a matrix plate resting upon said base and formed with at least two punching dies along a surface upon which said strip is adapted to rest, and with a first formation deviating from said surface and located between said dies;

a plurality of columns fixed with respect to said matrix plate and extending perpendicular to said surface;

a pressure-guide plate lying generally parallel to said surface and having a face confronting same, said pressure-guide plate being shiftably mounted on said columns for movement in a direction perpendicular to said surface;

spring means between said pressure-guide plate and said matrix plate for yieldably urging said pressureguide plate away from said matrix plate;

an insert removable mounted in said face of said pressure-guide plate and defining a second formation deviating from said face and complementary to said first formation on said surface of said matrix plate deflecting said strip upon displacement of said pressure-guide plate toward said matrix plate, said pressure-guide plate being formed with a pair of guide bores aligned with said dies in said direction;

a punch-carrying plate member mounted on said columns and disposed between said base and movable member of said press and said pressure-guide plate for movement in said direction;

a pair of punches mounted on said punch-carrying plate member and extending slidably through said bores for cooperation with said dies to form said strip, and

hydraulically pressurizable servo-motor means on at least one of said members and having a plurality of pistons connected with said pressure-guide plate for urging same in the direction of said matrix plate under a hydraulic pressure independent of the pressure applied by said movable member of said press to said punch-carrying plate member.

2. The tool defined in claim 1 wherein said insert projects from said face and has a pair of shaping surfaces including an angle between 17830' and 20' between them, said first formation is a recess, said dies have a converging angle between 04' and 015, and said bores each are formed by a sleeve mounted in said pressure-guide plate by a synthetic resin body, and said columns are positioned with respect to said plates by respective screws and washers.

1V t l i 

1. A tool for the forming of a metal strip in a press having a base and a member movable in the direction of said base, said tool comprising: a matrix plate resting upon said base and formed with at least two punching dies along a surface upon which said strip is adapted to rest, and with a first formation deviating from said surface and located between said dies; a plurality of columns fixed with respect to said matrix plate and extending perpendicular to said surface; a pressure-guide plate lying generally parallel to said surface and having a face confronting same, said pressure-guide plate being shiftably mounted on said columns for movement in a direction perpendicular to said surface; spring means between said pressure-guide plate and said matrix plate for yieldably urging said pressure-guide plate away from said matrix plate; an insert removable mounted in said face of said pressure-guide plate and defining a second formation deviating from said face and complementary to said first formation on said surface of said matrix plate deflecting said strip upon displacement of said pressure-guide plate toward said matrix plate, said pressure-guide plate being formed with a pair of guide bores aligned with said dies in said direction; a punch-carrying plate member mounted on said columns and disposed between said base and movable member of said press and saiD pressure-guide plate for movement in said direction; a pair of punches mounted on said punch-carrying plate member and extending slidably through said bores for cooperation with said dies to form said strip, and hydraulically pressurizable servo-motor means on at least one of said members and having a plurality of pistons connected with said pressure-guide plate for urging same in the direction of said matrix plate under a hydraulic pressure independent of the pressure applied by said movable member of said press to said punch-carrying plate member.
 2. The tool defined in claim 1 wherein said insert projects from said face and has a pair of shaping surfaces including an angle between 178*30'' and 155*20'' between them, said first formation is a recess, said dies have a converging angle between 0*4'' and 0*15'', and said bores each are formed by a sleeve mounted in said pressure-guide plate by a synthetic resin body, and said columns are positioned with respect to said plates by respective screws and washers. 